This is a five-year career development and research program to study mechanisms associated with lipid induced insulin resistance. The overall objective of this proposal is to determine the effects of lipid oversupply on lipid partitioning, mitochondrial capacity and insulin sensitivity within human skeletal muscle. I will complete the proposed career development and research program primarily at the Division of Endocrinology of the University of Pittsburgh under the direction of Dr. Bret Goodpaster. I will receive extensive training in clinical research methods and design as well as specific training with methods to assess insulin resistance in vivo and protein and gene expression in human muscle biopsy specimens. I will receive training in primary myocyte culture methodology under the direction of Dr. Charlotte Peterson at the University of Kentucky. Training in mass spectroscopy determination of skeletal muscle lipids will take place under the direction of Drs. Paul Baker and Bruce Freemen in the Department of Pharmacology at the University of Pittsburgh. This specific theoretic and practical training is directly related to my future plans to conduct obesity and diabetes research. More broadly, these experiences will build upon a foundation of basic science and clinical research and aid in my development as an independent translational scientist. My preliminary data suggests that aerobic exercise alters skeletal muscle lipid partitioning (increased triglycerides but lower diacylglycerol and ceramides) and these changes may be related to perturbations in lipid droplet proteins and enhanced mitochondrial content and/or capacity. Within this proposed period of training, I intend to extend this line of research to explore the possibility that alterations in the fatty acid composition of various lipid species (triglyceride, diacylglycerol and ceramide) may be causative in lipotoxic mediated insulin resistance. Acute in vivo studies of lipid oversupply, together with human primary cell culture techniques, will also be utilized to further explore pathways mediating improved insulin resistance, including mitochondrial capacity and changes in lipid droplet gene and protein expression. Supplemented by collaborations outside my primary Institution, the University of Pittsburgh is an ideal setting for me to develop professionally and begin a successful career as an independent translational research scientist. PUBLIC HEALTH RELEVANCE: I will study how too much lipid exposure to muscle may lead to the development of insulin resistance, a primary cause of type 2 diabetes. These studies will help us better understand the way in which exercise and diet can prevent or treat type 2 diabetes.